Analysis of Fracture Toughness Mechanism in Ultra-fine-grained Steels: The Effect of the Treatment Developed in NIMS

71 Pages·2014·4.031 MB·English

by  Toshihiro Hanamura, Hai Qiu (auth.)

NIMS Monographs
Toshihiro Hanamura
Hai Qiu
Analysis of
Fracture Toughness
Mechanism in
Ultra-fine-grained
Steels
The Effect of the Treatment Developed
in NIMS
NIMS Monographs
Series editor
Naoki OHASHI
Editorial board
Takahito OHMURA
Yoshitaka TATEYAMA
Takashi TANIGUCHI
Kazuya TERABE
Masanobu NAITO
Nobutaka HANAGATA
Kenjiro MIYANO
The NIMS Monographs are published by the National Institute for Materials
Science (NIMS), a leading public research institute in materials science in Japan,
in collaboration with Springer. The series present research results achieved by
NIMS researchers through their studies on materials science as well as current
scientific and technological trends in those research fields.
These monographs provide readers up-to-date and comprehensive knowledge
aboutfundamentaltheoriesandprinciplesofmaterialsscienceaswellaspractical
technological knowledge about materials synthesis and applications.
With their practical case studies the monographs in this series will be
particularly usefulto newcomers tothe field ofmaterials science and to scientists
and engineers working in universities, industrial research laboratories, and public
research institutes. These monographs will be also available for textbooks for
graduate students.
National Institute for Materials Science
http://www.nims.go.jp/
More information about this series at http://www.springer.com/series/11599
Toshihiro Hanamura Hai Qiu
(cid:129)
Analysis of Fracture
Toughness Mechanism
in Ultra-fine-grained Steels
The Effect of the Treatment Developed
in NIMS
123
Toshihiro Hanamura
Hai Qiu
National InstituteforMaterials Science
Tsukuba
Japan
ISSN 2197-8891 ISSN 2197-9502 (electronic)
ISBN 978-4-431-54498-2 ISBN 978-4-431-54499-9 (eBook)
DOI 10.1007/978-4-431-54499-9
LibraryofCongressControlNumber:2014946962
SpringerTokyoHeidelbergNewYorkDordrechtLondon
©NationalInstituteforMaterialsScience,Japan.PublishedbySpringerJapan2014
Thisworkissubjecttocopyright.AllrightsarereservedbytheNationalInstituteforMaterialsScience,
Japan (NIMS), whether the whole or part of the material is concerned, specifically the rights of
translation,reprinting,reuseofillustrations,recitation,broadcasting,reproductiononmicrofilms,orin
anyotherphysicalway,andtransmissionorinformationstorageandretrieval, electronicadaptation,
computer software, or by similar or dissimilar methodology now known or hereafter developed.
Exemptedfromthislegalreservationarebriefexcerptsinconnectionwithreviewsorscholarlyanalysis
ormaterialsuppliedspecificallyforthepurposeofbeingenteredandexecutedonacomputersystem,
for exclusive use by the purchaser of the work. Duplication of this publication or parts thereof is
permittedonlyundertheprovisionsofapplicablecopyrightlawsandapplicabletreaties,andpermission
forusemustalwaysbeobtainedfromNIMS.Violationsareliabletoprosecutionundertherespective
copyrightlawsandtreaties.
The use of general descriptive names, registered names, trademarks, service marks, etc. in this
publicationdoesnotimply,evenintheabsenceofaspecificstatement,thatsuchnamesareexempt
fromtherelevantprotectivelawsandregulationsandthereforefreeforgeneraluse.
While the advice and information in this book are believed to be true and accurate at the date of
publication,neithertheauthorsnortheeditorsnorthepublishercanacceptanylegalresponsibilityfor
any errors or omissions that may be made. NIMS and the publisher make no warranty, express or
implied,withrespecttothematerialcontainedherein.
Printedonacid-freepaper
SpringerispartofSpringerScience+BusinessMedia(www.springer.com)
Preface
The National Institute for Materials Science (NIMS) of Japan has long been
workingonresearchanddevelopmentprojectsrelatedtoadvancedsteels,andnow
the development of environmentally friendly steel products has become an urgent
necessity.Themainideaintheproduction-processprojectistoutilizetechnologies
for refined and ultra-refined steels. Mechanical properties of ultra-grain refined
steels are almost equivalent to those of conventional high-strength and high-
toughnesssteelsproducedwithrareandexpensivealloyingelements.Inthisbook,
advanced steels developed at NIMS, based primarily on unique structural con-
trolling process techniques, their mechanical properties, and their property
improvement mechanisms are presented and discussed. The following is an over-
view of each chapter.
Chapter 1 Introduction: Environmental Problems and Related Advanced Steel
Techniques (T. Hanamura)
Tensile strength and toughness of advanced steels are discussed from both the
fundamental and engineering points of view.
Chapter 2 Ultra-Fine-Grained Steel: Relationship Between Grain Size and Tensile
Properties (T. Hanamura)
Some phenomena in tensile properties unique to ultra-fine grained steels are pre-
sentedanddiscussed.Thesephenomenaincludeanincreaseinthestrain-hardening
rate with increasing carbon content up to 0.3 wt. % C and a strain-hardening rate
almost constant even with a further increase in carbon content.
Chapter 3 Ultra-Fine-Grained Steel: Relationship Between Grain Size and Impact
Properties (T. Hanamura)
Impactpropertiesuniquetoultra-finegrainedsteelsarediscussed.Theseproperties
include excellent fracture toughness owing to the steel’s characteristic small
effectivegrainsizeandhighsurfaceenergyoffractureincomparisonwiththoseof
other steel structures.
v
vi Preface
Chapter 4 Ultra-Fine-Grained Steel: Fracture Toughness (Crack-Tip-Opening
Displacement) (H. Qiu)
The variation tendency offracture toughness with ferrite grain size is discussed in
detail, and the fracture toughness of ultra-fine grained steel is evaluated.
Chapter 5 Summary (T. Hanamura)
The main focus of the book is summarized, namely the tensile strength and
toughnessofadvancedsteels from boththefundamental andengineering pointsof
view.
Acknowledgments
The authors acknowledge experimental support extended by Satoshi Iwasaki, Koji
Nakazato, Takaaki Hibaru, Syuji Kuroda, Yasushi Taniuchi, Sadao Hiraide,
Masayuki Komatsu, Goro Arakane, Masahiko Kawasaki, Noboru Sakurai, Elena
Bulgarevich, Aiko Takanabe, and Mai Tadono who have immensely helped in the
construction of this text book.
vii
Contents
1 Introduction: Issues Concerning Environmental Problems
and Related Advanced Steel Techniques . . . . . . . . . . . . . . . . . . . . 1
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2 Ultra-Fine Grained Steel: Relationship Between Grain Size
and Tensile Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.1 Grain Growth and Hall-Petch Relation in Ultra-Fine-Grained
Steel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.2 Dependence of the Strength and Strength-Elongation Balance
on Volume Fraction of Cementite Particles in Ultrafine Grained
Ferrite/Cementite Steels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.2.1 Experimental . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3 Ultra-Fine-Grained Steel: Relationship Between Grain Size
and Impact Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
3.1 DBTT Controlled by Effective Grain Size of Ultra-Fine
Ferrite/Cementite (UGF/C) Microstructure in Low
Carbon Steels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
3.1.1 Microstructure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
3.1.2 Charpy Impact Tests . . . . . . . . . . . . . . . . . . . . . . . . . . 31
3.1.3 Estimation of σ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
F
3.1.4 Estimation of γ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
3.1.5 Bimodal Distribution of Grain Size in UGF/C. . . . . . . . . 39
3.2 Low Absorbed Energy Ductile Dimple Fracture in Lower
Shelf Region in UGF/C Steel . . . . . . . . . . . . . . . . . . . . . . . . . 40
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
ix
x Contents
4 Ultra-Fine-Grained Steel: Fracture Toughness
(Crack-Tip-Opening Displacement). . . . . . . . . . . . . . . . . . . . . . . . 49
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
5 Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
5.1 Tensile Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
5.2 DBTT and Effective Grain Size. . . . . . . . . . . . . . . . . . . . . . . . 64
5.3 Crack Tip Opening Displacement. . . . . . . . . . . . . . . . . . . . . . . 64